Sounding device

ABSTRACT

In order to divide the inside space of the cabinet into at least two with a speaker being the center, obtain a plurality of emitted sound energies through openings constructed in each divided sphere, and utilize a cabinet of a loudspeaker apparatus as a sound echo box, a partition wall  4  is disposed at a right angle to a baffle board  2  or a front board  7,  passing through the center O of a speaker  3  disposed on the baffle board  2  or the front board  7  of the cabinet  6,  and divides the inside space of the cabinet  6  into at least two of an upper chamber  11 U and a lower chamber  11 D, so that sound energies are emitted from openings  8  and  9  which are provided in each chamber of  11 D and  11 U, respectively.

TECHNICAL FIELD

This invention relates to a loudspeaker apparatus suitable for use in anelectric guitar amplifier, and particularly, to the loudspeakerapparatus capable of being used not only as a speaker cabinet but alsoas a resonance amplifier box for an electric guitar.

BACKGROUND ART

Conventionally, with respect to an electric guitar amplifier(hereinafter referred to as a guitar amplifier), different types ofcabinets (enclosures) are used depending on the music to be played.

Specifically, a cabinet having a structure of open back box baffle,sealed box baffle, bass-reflex baffle, or the like is used, and sincehigh operating efficiency of a speaker is obtained and sound projectsforward out of the speaker, the open back baffle is suitable forreproducing such vivid and energetic sound as American sound. On theother hand, in this construction since sound is insufficientlyreproduced in bass range, the low-frequency component correction isconventionally performed by an equalizer in an amplifier side.

Then, the sealed box baffle is mainly used for reproducing loud soundsuch as a live music play, since the operating efficiency of a speakeris low, and in most cases four sets of speakers of 30 cm in diameter areaccommodated within the cabinet to be used by a number of musiciansproducing such hard sound as British rock.

Further, 99% of all the vented baffles (bass reflex) are used in a bassguitar amplifier and the insufficient sound reproduction in bass rangeis augmented by a bass reflex. The cabinet of bass reflex type is notused as a guitar amplifier. The reason is assumed that the quality ofsound in bass range reproduced by a duct may be far from that reproducedby a speaker.

Therefore, either open back box baffle or sealed box baffle is mostlyused for a guitar amplifier.

Further, there is conventionally used a cabinet for a guitar amplifier,which is made of thick wood boards of 18 mm to 25 mm in thickness; inorder to avoid scratches on the surface and to restrain an unnecessaryresonance, the outside surface of which is overlaid with a felt orvarious kinds of leather (vinyl-leather) similarly to the case of anconventional loudspeaker apparatus; corner sections of which arereinforced by metal fittings; and in which a speaker and an amplifiercircuit are accommodated.

When the sound is emitted through the above mentioned conventionalguitar amplifier, there arise a problem in which such acousticexpression as variety of timbre, sound echoes and multi-directionalemission of sound originally produced by the musical instrument, forexample, an electric guitar are not sufficiently reproduced.

When the above-described problem is further studied in relation to aguitar (what is called an acoustic guitar) and an electric guitar, theacoustic guitar has a body of a wooden box which functions as aresonance diffusing box, and emits fundamental tones generated by thestrings in simple harmonic motions and also from the body in multipledirections, emits sound of multiple phases having inherent timbreincluding various tone ratio, in which harmonic tones whose ratio isdetermined depending on the shape of the body are contained as thecontaining ratio of harmonics tone attenuates with a lapse of time,thereby producing sound inherent to a guitar.

On the other hand, since the electric guitar emits sound through aguitar amplifier by converting the vibration of metal strings intoelectric signals using an electro-acoustic transducer (pick-up) which isplaced under the strings on a resonance body of either resonance box orsingle board, it is difficult to achieve a sound expression inherent toa musical instrument such as variety of timbre, sound echoes andmulti-directional emissions of sound, which are produced by resonancediffusing box such as the acoustic guitar.

In other words, since the vibration of metal strings is picked up at asingle point and is emitted in a single direction as a sound energy, asound source is considered to be completely different from that of anacoustic guitar, in which every part of the body emits sound in multipledirections.

Even if an electric guitar is equipped with a resonance box, the soundgenerated by the resonance box is considerably low in comparison tomagnified sound from a guitar amplifier, and therefore it is consideredto be impossible to reproduce all of its inherent expression.

However, since the strings of the electric guitar are influenced bycomposite harmonic tones which are generated by a resonance board,electric signals converted from the vibration of metal strings carrycontents of various harmonic tones and sound echoes close to a livemusical instrument.

Accordingly, the object of the present invention is to provide aloudspeaker apparatus, which functions as a guitar amplifier (includinga speaker, a cabinet and an amplifier), capable of reproducing soundsimilar to that of a live musical instrument, in which electro-acousticsignals electrically converted from vibration by a pick-up become soundwith intrinsic features of an acoustic guitar, such as various harmonictones, echoes and multi-directional emissions of acoustic energy.

As described above, a cabinet used for the guitar amplifier is mostly ofeither open back box baffle, sealed box baffle or bass reflex and ismade of non-resonant solid thick wood boards; and since sound energiesare emitted in concentric waves from the center of a point where thespeaker is attached, there is no sound emission similar to those emittedfrom the body of an acoustic guitar, and in addition, a high frequencyrange is restrained by a felt or the like overlaid on the surface of thecabinet and sound signals are emitted as a reproduction sound close toelectric signals, which contains less harmonic tones. Accordingly, thesecond object of the present invention is to improve a cabinet(synonymous with an enclosure, a speaker box, a casing or a housing) soas to obtain a loudspeaker apparatus, in which multi-directionalemission of sound from the cabinet is increased, sound in a highfrequency range is not to be absorbed, the capability of reproducingsound in a high frequency range (harmonic tones) is enhanced and soundenergies of middle and low frequency range is capable of being emittedin multiple directions.

DISCLOSURE OF THE INVENTION

A first aspect of the present invention is a loudspeaker apparatus 1, inwhich a partition wall 4 provided at a right angle to approximately thecenter of a speaker 3 which is provided on a baffle board 2 divides thebaffle board 2 into at least two regions, so that sound energies areobtained from at least two divided regions.

A second aspect of the present invention is a loudspeaker apparatus 1,in which a partition wall 4 provided at a right angle to approximatelythe center of a speaker 3 that is installed on a front board 7 of acabinet 6 divides the inside space of the cabinet 6 into at least two toemit sound in middle and low frequency range from one of the dividedspace in the cabinet and to emit sound in middle and high frequencyrange from the other divided space in the cabinet.

A third aspect of the present invention is a loudspeaker apparatusaccording to the second aspect of the present invention, in which afirst opening 8 is provided on a bottom surface of one of the dividedspace in the cabinet, a second opening 9 is provided on a rear board ofthe other divided space in the cabinet, and the bottom surface on theside of the front board 7 is inclined at a predetermined angle.

A fourth aspect of the present invention is a loudspeaker apparatusaccording to the second or third aspect of the present invention, inwhich the partition wall 4 and the outside of the cabinet 6 are formedof wood boards and the surface thereof is mirror-finished with coatingmaterial such as lacquer or the like, whereby a whole cabinet is made tobe a resonance amplifier body.

A fifth aspect of the present invention is a loudspeaker apparatusaccording to the third or the fourth aspect of the present invention, inwhich the predetermined angle of inclination of the cabinet 6 is set to15°.

A sixth aspect of the present invention is a loudspeaker apparatusaccording to any one of the third to fifth aspects of the presentinvention, in which the first opening 8 on the bottom surface of thecabinet 6 is bored approximately right beneath a speaker 3 in the shapeof trapezoid, and the area of the trapezoid-shaped first opening isselected to be 80% of the horizontal cross section of a diaphragm 10 inthe speaker 3.

According to the loudspeaker apparatus of the first through the sixthaspects of the present invention, there is obtained the loudspeakerapparatus, in which through a plurality of added sound outlets sound isamplified to be emitted in multiple directions from the cabinetaccommodating a speaker, so that sound energies of different phaseswhich contains various harmonic tones similar to a musical instrumentare emitted, efficiency with respect to the emission is improved, andsince high-frequency components are reflected on the surface of thecabinet and the cabinet is light-weighted so as to function as aresonance body and to enhance the efficiency in reproducing highfrequency waves, there is reproduced sound emitted in multipledirections with a variety of timbre and sound echoes that is close tothat of a musical instrument such as an acoustic guitar.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are a front view and a fragmentary cross-sectional sideview, showing a loudspeaker apparatus according to an embodiment of thepresent invention;

FIGS. 2A to 2C are a fragmentary cross-sectional front view, afragmentary cross-sectional side view and an equivalent circuit diagram,showing a loudspeaker apparatus according to an embodiment of thepresent invention;

FIG. 3 is a fragmentary cross-sectional side view showing a loudspeakerapparatus according to an embodiment of the present invention;

FIG. 4 is a fragmentary cross-sectional bottom view showing aloudspeaker apparatus according to an embodiment of the presentinvention;

FIG. 5 is a fragmentary cross-sectional plan view showing a partitionwall of a loudspeaker apparatus according to an embodiment of thepresent invention;

FIG. 6 is a fragmentary cross-sectional rear view of a loudspeakerapparatus according to an embodiment of the present invention;

FIG. 7 is a fragmentary cross-sectional side view of a loudspeakerapparatus according to an embodiment of the present invention;

FIG. 8 is a diagram for explaining a state in which sound is emittedfrom a loudspeaker apparatus according to an embodiment of the presentinvention;

FIGS. 9A and 9B are a fragmentary cross-sectional front view and afragmentary cross-sectional side view of a loudspeaker apparatusaccording to another embodiment of the present invention;

FIGS. 10A and 10B are a fragmentary cross-sectional front view and afragmentary cross-sectional side view of a loudspeaker apparatusaccording to further another embodiment of the present invention; and

FIGS. 11A and 11B are fragmentary cross-sectional front views ofloudspeaker apparatuses according to yet further embodiments of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a structural principle of an embodiment of the presentinvention will be described with reference to FIGS. 1A and 1B, and FIGS.2A to 2C.

FIGS. 1A and 1B are a front view and a cross-sectional side view showinga state in which a speaker of a loudspeaker apparatus 1 according to thepresent invention is installed on a baffle board; and FIG. 2A is afragmentary cross-sectional front view of the loudspeaker apparatus ofthe present invention, FIG. 2B is a cross-sectional perspective viewtaken by A-A in FIG. 2A, and FIG. 2C is an equivalent circuit diagram ofthe loudspeaker apparatus according to the present invention.

In the loudspeaker apparatus shown in FIG. 1, a speaker 3 is fixed to anopening 5, which has the diameter corresponding to that of the speaker 3and is bored on roughly the center of an approximately rectangularfinite baffle board 2, such that the speaker 3 opposites to the opening5; and further, a partition wall 4 is fixed at a right angle to thevertical plane of the baffle board 2 with the partition wall passingthrough the center O of the opening 5 or the diaphragm 10 of the speaker3 to be parallel with the short side direction of the rectangular baffleboard 2, so that the partition wall 4 divides the baffle board 2 into atleast two regions, that is, upper and lower regions.

When the speaker 3 is actuated under the above-described condition, inaddition to the concentric emission of sound energy from the opening 5of the speaker 3, at least, forward and backward emissions of soundenergies F_(F1) and F_(B1) from the lower region of the baffle board 2under the partition wall 4 and forward and backward emissions of soundenergies F_(F2) and F_(B2) from the upper region of the baffle board 2above the partition wall 4 are obtained.

Although in the above explanation the rectangular baffle board 2 isdivided into two regions of upper and lower, when the partition wall 4is fixed to be parallel with the long side of the baffle board 2 at aright angle to the vertical plane of the baffle board 2 with thepartition wall passing through the center O of the opening 5 or thespeaker 3, as shown by the virtual chain lines, so that the baffle board2 is divided into two regions of left and right about the speaker 3,then in addition to forward emission of sound energy F_(F) from theopening 5 of the speaker 3, there are obtained forward and backwardemissions of sound energies by way of the left side end and the top andbottom ends from the left region of the baffle board 2 divided by thepartition wall 4 and emissions of sound energies from the right regiondivided by the partition wall 4.

Obviously, when the above mentioned two partition walls 4 and 4 areprovided crosswise, that is, horizontally and vertically to divide thebaffle board 2 into four regions, sound emitted from a single speakercan increase twice as much in comparison to a case when no partitionwall is installed.

As shown in FIGS. 2A and 2B, the loudspeaker apparatus 1 has anoblong-shaped cabinet 6 like an conventional guitar amplifier, in whichthe opening 5 is bored on the center of a front board 7 which functionsas a baffle board with the speaker 3 being fixed in the positionopposite to the opening 5; and the partition wall 4 is fixed to beparallel with top and bottom boards of the cabinet at a right angle tothe vertical surfaces of the front board 7 and a rear board passingthrough the center O of the speaker 3, thereby dividing the cabinet toform an upper chamber 11U and a lower chamber 11D.

Obviously, the portion of the partition wall 4, where the speaker 3 isengaged, is carved to fit to the form of the speaker 3 such as a framethereof so that a gap is not created between the partition wall and theouter appearance of the speaker as much as possible.

A first opening 8 is bored on the bottom board of the lower chamber 11Dright beneath the speaker 3 and the rear board is sealed hermetically. Agroove-shaped second opening 9 is bored on the rear board of the upperchamber 11U along the partition wall 4 and its top board is sealedhermetically, and the upper chamber 11U and the lower chamber 11D areconstructed to have approximately the same cubic volume.

When the speaker 3 in the loudspeaker apparatus 1 as constructed aboveis actuated by inputting predetermined sound signals to terminals a andb, the operation can be described by an equivalent circuit shown in FIG.2C.

In FIG. 2C, when the concentric sound energy at a predetermined time andfrequency, which is emitted forward through the opening 5 of the frontboard 7 constituting a baffle board of the cabinet 6, is F_(F)=fE, thesound energy F_(D) emitted downward from the first opening 8 of thelower chamber 11D is reflected on a floor to be a forward sound energyF_(F1) with the front board 7 of the cabinet 6 being lifted up at apredetermined angle, and this sound energy F_(F1) and the sound energyF_(B2) emitted backward from the second opening 9 on the rear board ofthe upper chamber 11U are both one half of the total sound energy fEemitted from the speaker 3 carrying a reverse phase and are expressed asF_(F1)=F_(B2)=−fE/2.

If those energies emitted from the first and second openings carry thesame phase as that of sound energy F_(F)=fE from the front, thoseenergies are expressed as fE+|−fE/2|=1.5fE. If they carry a reversephase, the expression becomes fE+(−fE/2)=0.5fE. In case of delayedphase, they become a sum or subtraction wave, since they each fall intothe range of 1.5fE>X>0.5fE, in average, it is assumed that the soundenergy X=1.0fE is emitted from two virtual active speakers 12D and 12Uthrough the first and second openings 8 and 9.

In the present invention, the first opening 8 provided in the lowerchamber 11D of the cabinet 6 has different functions from a conventionalbass reflex, which reverses a phase of backward sound energy byutilizing resonance at certain narrow band frequencies and emits thebackward sound energy toward forward direction; and in this inventionthe lower chamber 11D including the first opening 8 as a whole are madeto be a resonance amplifier body, in which energy larger than theoriginal live sound of a musical instrument (an electric guitar) whichis generated by the speaker 3, that is one half fE/2 of the total energyfE in this case, is reflected on the floor constituting infinite baffleto be emitted forward and the sound emitted forward from the speaker 3is augmented.

When the quality of sound which is emitted through the above mentionedfirst opening 8 in the lower chamber 11D is studied, although the soundreproduced by the speaker 3 in the cabinet 6 originally contains allfrequencies which the speaker 3 can reproduce, through the reflection ina room 15 (refer to FIG. 8) and also through the reflection at a floor18 (refer to FIG. 8) which constitutes an infinite baffle, a highfrequency range is mainly attenuated but the attenuation ratio of a lowfrequency range, which is the principal feature, is relatively smallerin comparison with the high frequency range. Therefore, components inlow and middle frequency range are relatively augmented and emitted.

Especially by making use of the floor 18 as an infinite baffle, thereproduction of a low frequency range (including components of middlefrequencies) can achieve the maximum level according to the feature ofan infinite baffle, and energies of the low and middle frequency rangereflected by the floor 18 are added to the original sound emitted fromthe front of the speaker 3, thereby producing an effectiveness ofmagnifying low (including middle) frequency range.

On the other hand, the second opening 9 in the upper chamber 11U doesnot have an infinite baffle suitable for reproducing a low frequencyrange, compared to the floor 18 for the lower chamber 11D, and thereforehas no such effectiveness as to reinforce mainly a low frequency range.

However, since the upper surface of the partition wall 4 ismirror-finished by coating nitro-cellulose lacquer, a high frequencyrange is efficiently reflected and emitted from the opening 9 in theupper chamber 11U. Therefore, quality of sound emitted from the secondopening 9 in the upper chamber 11U contains relatively larger amounts ofhigh (including middle) frequency components in comparison with qualityof sound emitted from the first opening 8 in the lower chamber 11D.

Further, from the second opening 9 in the upper chamber 11U largeamounts of emitted sound energy extend around the cabinet 6, because ofthe position of the opening 9 constructed on the cabinet, and asmentioned above, the mirror-finish in lacquer coating enhances diffusedreflection in a high frequency range so as to obtain sound includingvarious phases emitted in multiple directions similar to thoseoriginally emitted by a musical instrument.

FIG. 2C is an equivalent circuit diagram of an electrical speakershowing the above described phenomena. Since the values of circuitconstant R, C1 and C2 are determined depending upon dimensions and ashape of the cabinet, required constants can be determined based on thepurpose for which a loudspeaker apparatus is used.

Next, referring to FIGS. 3 to 6, the construction of the loudspeakerapparatus 1 of a guitar amplifier according to an embodiment of thepresent invention will be explained in detail. FIG. 3 is across-sectional side view of the loudspeaker apparatus 1; FIG. 4 is afragmentary cross-sectional rear view; FIG. 5 is a fragmentarycross-sectional bottom view; and FIG. 6 is a fragmentary cross-sectionalplan view of a partition wall. The same reference numerals are given tothose corresponding to the ones in FIG. 2A and 2B.

As shown in FIGS. 3 through 6, a cabinet 6 has oblong parallelepipedshape, in which at the center of a rectangular front board 7constituting a baffle board a opening 5 having the same diameter as thatof a speaker 3 is made to fix such that the speaker 3 is opposite to theopening 5.

The cabinet 6 is formed of rectangular wooden boards of: a top board 6U,a bottom board 6D, left and right side boards 6L, 6R, and first andsecond rear boards 6B₁, 6B₂ to be approximately box-shaped.

The material for the cabinet 6 of the present invention is differentfrom a conventional single panel of American larch whose thickness is 18mm or more, and is a laminated board made of Mercusi pine (Laos pine) ofthe thickness selected to be about 14 mm. Since the Mercusi laminatedboard is light-weighted and resonant frequencies thereof arediversified, the cabinet 6 is designed such that, similarly to the bodyof a violin, the top board 6U, the bottom board 6D, the left and rightboards 6L, 6R, the first and second rear boards 6B₁, 6B₂, and thepartition wall 4, which is described later, can adequately bend whenvibrating at a maximum amplitude.

Inside the cabinet 6, the partition wall 4 is fixed as shown in FIGS. 3and 6. This partition wall 4 is fixed through the center O of theopening 5 or the speaker 3 parallel with the top board 6U and the bottomboard 6D, and at a right angle to the inside surfaces of the front board7, the first rear board 6B₂ and the left and right side boards 6L, 6R,thereby dividing the inside of the cabinet into two divided space toform an upper chamber 11U and a lower chamber 11D, both of which haveapproximately the same cubic volumes.

As shown in FIG. 6, a funnel-shaped cutting portion 13 is formed along aframe 12 of the speaker 3 at the front edge of the rectangular partitionwall 4. The gap 14 between the cutting portion 13 and the frame 12 ofthe speaker 3 is constructed to be kept minimum that is not more than 5mm.

As shown in FIGS. 3 and 4, a first opening 8 is bored on the bottomboard 6D of the cabinet 6 right beneath the speaker 3. The first opening8 is shaped like a funnel-like isosceles trapezoid with the base thereofon the side of the front board 7 and the upside thereof on the side ofthe rear board 6B₂, and has a large area (for example, the base 25cm×the upside 20 cm×the height 5 cm).

The area of the first opening 8 which has the above-mentioned shape ofthe isosceles trapezoid is determined depending upon the speaker 3 to beused, and is equivalent to approximately 80% of the horizontalcross-sectional area of the diaphragm 10 of the speaker 3 when thespeaker 3 has a diameter of about 30 cm. In the case where the area islarger than the horizontal cross-sectional area of the diaphragm 10 (forexample, more than 150%), the emitting velocity of the sound energybecomes slow and, as a result, the energy emitted from the first opening8 is made to contain high frequency sound components. On the other hand,when the area of the first opening 8 is made smaller to about 50% of thehorizontal cross-sectional area of the diaphragm 10, it is verified thatthe same effect as a bass reflex occurs. As mentioned above, thisinvention is not for obtaining a function of a bass reflex but forobtaining a throttling effect with respect to the emission of soundenergy so that emitting speed becomes faster and the range of resonantfrequencies becomes wider.

As shown in FIGS. 3 and 4, the rear surface of the lower chamber 11Dunder the partition wall 4 is sealed up with the second rear board 6B₂,which has the same thickness as the bottom board 6D. In practical use,as shown in FIG. 4, protruding portions 16L, 16R which protrude from thepartition wall 4 are formed in the vicinity of the left and right sideboards 6L, 6R.

Further, with respect to the upper chamber 11U, as shown in FIGS. 3 and4, the top board 6U is made of a board having the same thickness as thepartition wall 4, and along the partition wall 4 the second opening 9 isbored on the first rear board 6B₁.

The second opening 9 is shaped like an approximately rectangle whosewidth is narrower in the vicinity of the left and right side boards 6L,6R and wider at the center. In order to obtain the second opening 9,protrusions 17L, 17R are formed opposing to 16L, 16R at left and rightpositions at the bottom edge of a rectangular board which is slightlythinner than the rear board 6B₂, and the sound emitting energy ofapproximately 1.0fE, which is obtained in the upper chamber 11U, isemitted through this second opening 9. The reason for providing theabove described shape, which is narrower in the vicinity of the left andright side boards 6L, 6R and wider at the center when the cabinet 6 isseen from the rear, is that the emitted sound energy F_(B2) from theleft and right side boards 6L, 6R to the second opening 9 becomes lessin the center of the speaker 3 due to the magnet and the bottom yoke;and that the throttling effect of the emitting sound energy F_(B2)increases in the vicinity of the left and right side boards 6L, 6R.

In addition, the cabinet 6 is mirror-finished by coating nitro-celluloselacquer on the outside surfaces of the top board 6U, the left and rightside boards 6L, 6R and the bottom board 6D, on the upper surface of thepartition wall 4 (the side of the upper chamber 11U), and on the wallsinside the upper chamber 11U, so that similar to the body of a violinhigh frequency sound which extends around the cabinet 6 is made toreflect, harmonic tones can be reproduced, and the capability ofreproducing a high frequency range is made to be improved.

Moreover, a predetermined roundness R is provided on the periphery ofthe first and second openings, the top board 6U, the bottom board 6D andthe left and right side boards 6L, 6R, so that the effect of thediffused reflection with respect to the emitted sound energy can besmoothed.

Next, referring to FIGS. 7 and 8, a loudspeaker apparatus according toan embodiment of the present invention will be explained in detail. FIG.7 is a cross-sectional side view showing the loudspeaker apparatus whichis being operated. FIG. 8 is a schematic diagram for explaining a statein which sound wave is emitted.

The loudspeaker apparatus 1 shown in FIG. 7 is equipped with an foldingleg 19 at the front part of the bottom board 6D of the cabinet 6 and thelength thereof is selected to obtain an angle of θ=15° between thebottom board 6D of the cabinet 6 and the floor 18 when the leg isunfolded. In addition, length of the short sides of the top board 6U andthat of the bottom board 6D of the cabinet 6 are different so that thefirst rear board 6B₁ becomes unparallel to the front board 7, therebyincreasing the sound energy with respect to middle and high frequencyrange emitted from the second opening 9 and extended along the cabinet.

The cubic volume of the upper chamber 11U and the lower chamber 11D inthe cabinet 6, which is divided by the partition wall 4, is selected tobe approximately equal; and the width (short side of the rectangleshape) of the bottom board 6D is 240 mm and long side thereof is 520 mmin length; the height of the cabinet 6 is 375 mm; and the thickness ofMercusi pine laminated board constituting the cabinet 6 and thepartition wall 4 is selected to be 14 mm.

An electro-dynamic type loudspeaker of 30 cm in diameter is selected tobe a speaker 3 which is fixed to the front board 7.

The first opening 8 bored on the bottom board 6D is in the shape of anisosceles trapezoid having the dimensions in which the base is 260 mm,the upside is 210 mm, and the height is 50 mm, and the base of thetrapezoid is located at 40 mm behind the fixing position of the frame ofthe speaker 3.

The gap between the frame 12 and the funnel-shaped cutting portion 13 onthe partition wall 4, which is formed along the frame 12 of the speaker3, is set to be 3 mm, and the second opening 9 formed between the firstrear board 6B₁ and the partition wall 4 is selected to be 372 mm inlength and 77 mm in width at the wider portion thereof and 60 mm inlength and 37 mm in width at the narrower portions thereof, which areformed in the vicinity of the left and right side boards 6L and 6R.

FIG. 8 shows the state of emitting sound, in which the above describedloudspeaker apparatus 1 is disposed at a predetermined position in apredetermined chamber 15 with the leg 19 unfolded and the opening 5 ofthe speaker 3 at an angle of 15° lifted upward from the floor 18.

When the speaker 3 is actuated in the loudspeaker apparatus 1 shown inFIG. 8, concentric waves of sound energies indicated by arrows of 0° and±15° are emitted obliquely upward from the opening 5 of the speaker 3and emission waves of ±30° are reflected by the floor 18 and the ceiling20. Conventionally, a speaker 3 in a guitar amplifier has frequencycharacteristics of 160 Hz to 2000 Hz with a low band resonant frequencyf₀ at about 80 Hz to 100 Hz and a frequency characteristic compensationis performed so as to increase the level of high and low frequencyrange.

Further, emission wave at an angle of −15° reflected on the floor, whichcontains harmonic tones in middle and low frequency range of, forexample, 1.0fE emission energy is obtained from the first opening 8 inthe lower chamber 11D through the reflection on the floor 18. In thiscase, harmonic tones in a low frequency range, which is emitted from thefirst opening 8, reaches audiences in front through the reflection onthe floor 18 as an infinite baffle.

On the other hand, from the second opening 9 bored on the first rearboard 6B₁ of the upper chamber 11U, waves in middle and high frequencyrange having, for example, 1.0fE emission energy reflected on a wall 21and the ceiling 20—A, waves reflected on the wall and a ceiling—B andthe like, which are emitted after reflecting on the top board 6U and thepartition wall 4 are emitted to the audiences further in front.

In the present invention, with respect to the phase of sound emittedfrom the opening 5 and the first and second openings 8 and 9 of thespeaker 3, the audience listens to a finalized composite sound wave inwhich phases such as an synchronous phase, a reverse phase and delayedphases, are emitted and synthesized into a composite sound in a space(chamber 19) and perceives the composite sound waves as the soundgenerated by a musical instrument (loudspeaker apparatus 1).

According to the present invention, in the loudspeaker apparatus 1 soundenergies are emitted from the three openings, which are the front of thespeaker 3 and the first and second openings, and in addition, theoutside of the cabinet 6 and the partition wall 4 are coated withlacquer or the like and mirror-finished to enhance sound emissions inmultiple directions, whereby the loudspeaker apparatus 1 generates soundhaving rich variation of harmonic tones similar to that of a musicalinstrument, makes sound waves of various phases efficiently reflect inmultiple directions, and as a whole, can be utilized as the loudspeakerapparatus 1 virtually reproducing rich sound field expression similar tothat of a musical instrument.

In the above embodiment of the present invention, while the internalspace of the cabinet 6 is divided by the partition wall 4 into two ofthe upper chamber 11U and the lower chamber 11D, the gap 14 isunavoidably made between the partition wall 4 and the frame 12 of thespeaker 3. In addition, since there is also some gap between the frame12 and the diaphragm 10, air can naturally move between the upperchamber 11U and the lower chamber 11D. However as the amplitude of thespeaker 3 approaches to its maximum, the less air flows between theupper chamber 11U and the lower chamber 11D, which is similar to theeffect of an air curtain, thereby enabling the cabinet to be used asthat having upper and lower two divided chambers.

In other words, when larger sound in volume is being produced, theamplitude of the speaker 3 is conventionally large enough to generatedynamic force of moving air (to-and-fro kinetic force with respect tothe cabinet 6), which surpasses the force of air moving through the gap14 between the upper chamber 11U and the lower chamber 11D.

Accordingly, each divided space of the upper and lower chambers isestimated to have 70% to 80% air-tightness under the normal operation,though it is not 100% hermetically sealed.

When the speaker 3 of the above mentioned loudspeaker apparatus in FIG.7 is actuated and emitted sound is listened to in a predetermined space,

-   1) there is no considerable disorder with respect to the sound    phase;-   2) there are more energies emitted from the first and second    openings;-   3) the emitted air waves contain a comfortable tremor of 3 Hz to 4    Hz;-   4) at an ordinary playing position, which is 3 m to 4 m away from    the cabinet 6, from low to middle frequency range is definitely    compensated and reinforced;-   5) a boarded floor is more effective than a carpeted floor.-   6) if openings are fully sealed, there is no effectiveness observed;    and-   7) though the richest sound close to a musical instrument is    reproduced at the tilt angle of 15°, deviation up or down from 15°    does not change the point where the maximum efficiency is obtained.    Because of the mirror-finish by coating nitro-cellulose lacquer,-   8) when the emitted sound waves extend around the cabinet, diffused    reflections are caused to generate pleasant echoes of a high    frequency range; and-   9) in addition, the upper part and surface of the partition wall    efficiently reflect and emit a half of the sound energy emitted    backward and (depending on the surroundings where the loudspeaker    apparatus is placed), thereby forming a sound field which is close    to “echoes of a musical instrument”.

As a result, compared to a conventional guitar amplifier which has afelt or leather overlaid on the surface and suppresses the reflection ofa high frequency range as much as possible, the loudspeaker apparatus 1according to the present invention reproduces sufficient sound echoes asa musical instrument.

In the above construction, the internal space of the cabinet 6 isdivided into two of either upper and lower chambers or left and rightchambers. Then, referring to FIGS. 9 through 11, another embodiment of aloudspeaker apparatus according to the present invention will beexplained in detail.

FIGS. 9A and 9B are a fragmentary cross-sectional front view and afragmentary cross-sectional side view showing an internal space of acabinet 6 which is divided into four of a first to a fourth chambers byfixing crosswise a first partition wall 4 which is fixed through thecenter O of a speaker 3 parallel with a top board 6U and a bottom board6D and at a right angle to inner surfaces of left and right side boards6L and 6R, and a second partition wall 23 which is also fixed throughthe center O of the speaker 3 parallel with the left and right sideboards 6L and 6R and at a right angle to inner surfaces of the top board6U and the bottom board 6D, when viewed from the front. Then, secondopenings 9 a and 9 b are bored on the first rear board 6B₁ in the upperfirst and second chambers respectively, and first openings 8 a and 8 bare bored on the bottom board 6D in the lower third and fourth chambers,respectively. According to the above construction, in addition to asound emitted from the front of the speaker 3 sound is emitted from thetwo openings of the rear board 6B₁ and the two openings of the bottomboard 6D and all of those emitted sound signals can be synthesized to bea composite sound in a space.

FIG. 10A is a fragmentary cross-sectional front view; and FIG. 10B is afragmentary cross-sectional view in the direction shown with arrow A inFIG. 10A; and the shape of the cabinet 6 is a regular hexahedron.

In FIGS. 10A and 10B, the inside of the cabinet is diagonally divided bya partition wall 4, as shown in FIG. 10A, to form upper and lower (orleft and right) two rectangular-pole shaped space, and first and secondopenings 8 and 9 are bored on the bottom board 6D and the rear board6B₁, respectively. In this case, as shown with virtual lines in FIG.10A, two partition walls 4 may be disposed crosswise in diagonaldirections to divide the cabinet into quarters: a first through a fourthtriangular-pole shaped quadrant chambers 28 a through 28 d, and, withrespect to the third chamber 28 c, the first opening 8 may be bored onthe left side board thereof.

FIG. 11A shows the construction in which a speaker 3 is fixed to a frontboard 7 of a cylindrical cabinet 6 whose inside space is divided intoeight by four partition walls 4 a, 4 b, 4 c and 4 d, and first openings8 a through 8 h are formed on side walls of respective space and secondopenings 9 a through 9 h are formed on a rear board 6B, thereby emittingsound from 17 outlets in total.

FIG. 11B shows the construction in which a domed cabinet whose inside isdivided into upper and lower space at the base of the dome is providedto form the dome portion 25 and the cylindrical portion 26, the cubicvolume of which is different to each other.

Although in the above-described construction, a loudspeaker apparatusapplied to a guitar amplifier is explained in detail, the presentinvention can be applied to a speaker box for reproducing a CD and thelike to obtain the speaker box having rich sound echoes including soundemissions and the reproduction characteristics of harmonic tones,thereby providing such an affluent musical expression as a concert hallhas.

With respect to the shape of the cabinet, the same shape as a musicalinstrument such as a violin or the like is employed to utilize its ownfeatures, which are determined depending on the shape of the cabinet 6,such as producing harmonic tones, emitting sound in multiple directionsand sound echoes. In this case a partition wall of the present inventioncan be correspond to a prop stick of a violin or the like.

According to a loudspeaker apparatus of the present invention,

-   a) the inside space of a speaker can be divided into at least two of    either upper and lower, or left and right to emit sound, in which    middle and high frequency range and low and middle frequency range    are diffused and reinforced, from the divided space;-   b) a cabinet is lifted up at an angle of 15° from a floor to emit    sound energy in the front direction from a first opening facing the    floor, thereby compensating and reinforcing the original sound    emitted from the front surface of the speaker;-   c) the outside surfaces of a top board and left and right side    boards, and the upper surface of a partition wall are    mirror-finished by coating nitro-cellulose lacquer, thereby    enhancing the reflection efficiency of a high frequency range to    cause the reproduction of harmonic tones, and as the result, the    timbre inherent to a musical instrument can be reproduced; and-   d) from an opening provided on a rear board, more sound energies are    emitted to a wall behind or the like with a partition wall being    utilized as a reflector, thereby reinforcing the reproduction of “a    sound field intrinsic to a musical instrument”.

INDUSTRIAL APPLICABILITY

According to a loudspeaker apparatus of this invention, sound similar tothat of a live musical instrument can be emitted from an electric guitaramplifier (a cabinet for a guitar amplifier), and therefore thisloudspeaker apparatus is suitable for use in a speaker apparatus(speaker box) for audio equipment such as a conventional recording andreproducing apparatus and also in a speaker apparatus which includes aspeaker within a housing (a casing or an enclosure) of an electronicapparatus such as a radio, a CD player and the like.

1. A loudspeaker apparatus, in which a partition wall provided at aright angle to the center of a speaker that is provided on a baffleboard divides the baffle board into at least two regions to obtain soundenergies emitted from at least two divided regions.
 2. A loudspeakerapparatus, in which a partition wall provided at a right angle to thecenter of a speaker that is installed on a front board of a cabinetdivides the inside space of the cabinet into at least two to emit soundin middle and low frequency range from one of the divided space in thecabinet and to emit sound in middle and high frequency range from theother divided space in the cabinet.
 3. A loudspeaker apparatus accordingto claim 2, wherein a first opening is provided on a bottom surface sideof said one of divided space in the cabinet and a second opening isprovided on a rear board of the other divided space in the cabinet, andthe front edge of the bottom board of the cabinet is tilted at apredetermined angle.
 4. A loudspeaker apparatus according to claim 2,wherein the outside of said cabinet and said partition wall are made ofwood and surfaces thereof are mirror-finished by coating lacquer or thelike to make the whole cabinet become a resonance amplifier box.
 5. Aloudspeaker apparatus according to claim 3, wherein the predeterminedtilt angle of said cabinet is set to 15°.
 6. A loudspeaker apparatusaccording to claim 3, wherein said first opening on the bottom surfaceof said cabinet is bored approximately right beneath said speaker and istrapezoid in shape, and the area of the trapezoid-shaped opening isselected to be 80% of the horizontal cross-sectional area of a diaphragmof the speaker.